From 54c4f3405747bc637c5bb286f1c70510d1ef3a2b Mon Sep 17 00:00:00 2001
From: David Wells <drwells@email.unc.edu>
Date: Sun, 8 Jul 2018 13:31:14 -0400
Subject: [PATCH] step-9: Make the implementation match the documentation.

There was a disconnect between what was described in the introduction and the
actual class implementation.
---
 examples/step-9/doc/intro.dox | 8 ++++++--
 examples/step-9/step-9.cc     | 6 +++---
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/examples/step-9/doc/intro.dox b/examples/step-9/doc/intro.dox
index 0bd0a51c54..1bd0412c5c 100644
--- a/examples/step-9/doc/intro.dox
+++ b/examples/step-9/doc/intro.dox
@@ -197,6 +197,10 @@ the following domain and functions (in $d=2$ space dimensions):
     \begin{array}{c}2 \\ 1+\frac 45 \sin(8\pi x)\end{array}
   \right),
   \\
+  s
+  &=&
+  0.1,
+  \\
   f({\mathbf x})
   &=&
   \left\{
@@ -215,7 +219,7 @@ the following domain and functions (in $d=2$ space dimensions):
   \\
   g
   &=&
-  e^{5(1-|{\mathbf x}|^2)} \sin(16\pi|{\mathbf x}|^2).
+  e^{5 (1 - |\mathbf x|^2)} \sin(16\pi|\mathbf x|^2).
 @f}
 For $d>2$, we extend $\beta$ and ${\mathbf x}_0$ by simply duplicating
 the last of the components shown above one more time.
@@ -242,7 +246,7 @@ cell $K$ the following indicator:
 @f[
   \eta_K =
   \left(
-    \frac {h_K}{12}
+    \frac {h_K}{24}
     \int_{\partial K}
       [\partial_n u_h]^2 \; d\sigma
   \right)^{1/2},
diff --git a/examples/step-9/step-9.cc b/examples/step-9/step-9.cc
index ad29716a41..72cfe5f31f 100644
--- a/examples/step-9/step-9.cc
+++ b/examples/step-9/step-9.cc
@@ -312,9 +312,9 @@ namespace Step9
     (void)component;
     Assert(component == 0, ExcIndexRange(component, 0, 1));
 
-    const double sine_term = std::sin(16. * numbers::PI * p.norm());
-    const double weight    = std::exp(-5. * p.norm_square()) / std::exp(-5.);
-    return sine_term * weight;
+    const double sine_term = std::sin(16. * numbers::PI * p.norm_square());
+    const double weight    = std::exp(5. * (1. - p.norm_square()));
+    return weight * sine_term;
   }
 
   // @sect3{GradientEstimation class declaration}
-- 
2.39.5